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Author Topic: membrane bass traps thickness  (Read 13422 times)

Bruno Gouveia

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Re: membrane bass traps thickness
« Reply #15 on: February 02, 2009, 07:42:04 pm »

Very interesting! The absorption as described makes sense and it will lower the sound levels in a room, but for music rooms will it work?  

http://www.ntnu.no/gemini/2006-01e/deamp.htm I've followed this article in the press section of their site. The metal absorbers, thin as they are likely to sing like a bird, and we already know re-radiations can be very dangerous to music...

Bruno Gouveia

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Re: membrane bass traps thickness
« Reply #16 on: February 02, 2009, 07:51:14 pm »

Thomas Jouanjean wrote on Mon, 02 February 2009 18:32



Manufacturer's data (when available) and discussion with specialists -> real-life / empirical testing -> Data to software (MATLAB etc) -> estimation within the desired confidence interval.

Then real-life test in situ. With time you build-up a database, that you refine constantly.

To design studios, I work both in B&K ODEON and AUTOCAD (to draw plans)





I've a friend who is a mechanical engineer and his job is to design boxes to hold electronic PCB that must endure extreme and severe conditions like a rocket launch and space. He uses a software called NASTRAN http://www.mscsoftware.com/products/msc_nastran.cfm?Q=131&am p;Z=396&Y=422 that seems really powerful in predicting vibration modes.

The other day I picked up this book http://www.amazon.com/Vibration-Analysis-Electronic-Equipmen t-Steinberg/dp/047137685X/ref=sr_1_1?ie=UTF8&s=books& ;qid=1233622036&sr=8-1  at his house and it was very well written, definitely very useful to have around for anyone deeply interested in acoustics and it had very clear concepts and I've never see described like it's author, Dave S. Steinberg

Thomas Jouanjean

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Re: membrane bass traps thickness
« Reply #17 on: February 03, 2009, 02:59:30 am »

Bruno Gouveia wrote on Mon, 02 February 2009 18:42

Very interesting! The absorption as described makes sense and it will lower the sound levels in a room, but for music rooms will it work?  

http://www.ntnu.no/gemini/2006-01e/deamp.htm I've followed this article in the press section of their site. The metal absorbers, thin as they are likely to sing like a bird, and we already know re-radiations can be very dangerous to music...



I've considered only the ones in Acrylic for now, the transparent ones. The radio station we are designing now wants to have huge window surface in their studio (over 2/3 of all the walls) which obviously goes against the needed acoustic performance of the space. So this product in combination with more classical systems will be great!

The transparent ones are rather thick it seems (4mm to 10mm) so re-emission *should* be limited... Using them in the radio studio will work without problems I'm sure as the conditions needed are not as extreme as in a recording or mastering studio (response and SPL wise).

http://www.deamp.com/?shw=PRDPNL

Moreover, they allow to keep the light in - which will make the client happy. If you want, I'll share the results of our first shot at them?
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Thomas Jouanjean
Northward Acoustics - Engineering and Designs
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Thomas Jouanjean

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Re: membrane bass traps thickness
« Reply #18 on: February 03, 2009, 03:04:34 am »

Bruno Gouveia wrote on Mon, 02 February 2009 18:51


I've a friend who is a mechanical engineer and his job is to design boxes to hold electronic PCB that must endure extreme and severe conditions like a rocket launch and space. He uses a software called NASTRAN  http://www.mscsoftware.com/products/msc_nastran.cfm?Q=131&am p;am p;Z=396&Y=422 that seems really powerful in predicting vibration modes.



NASTRAN seems very interesting, thanks for the tip. Does it work well for smaller surfaces?

I noticed that the smaller the surface, the less accurate the estimation. Did you use it yourself?


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Thomas Jouanjean
Northward Acoustics - Engineering and Designs
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Bruno Gouveia

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Re: membrane bass traps thickness
« Reply #19 on: February 03, 2009, 03:48:49 am »

Thomas Jouanjean wrote on Tue, 03 February 2009 08:04



NASTRAN seems very interesting, thanks for the tip. Does it work well for smaller surfaces?

I noticed that the smaller the surface, the less accurate the estimation. Did you use it yourself?





Sure it does! The box he's currently designing is the size of a fooball ball (it will be a part of a satellite that is to travel to Jupiter!)  and the parts have resonances in the 0.7k - 3k Hz range. I've never used the software but I've seen him working and he gave me a small presentation of the capabilities of it. For instance, the possibilities to insert the variables that are used to define a material can be made to a great level of detail. But I plan to steal him more time! Wink

There's other people that are using this software to help them make carbon fiber electrical guitars  http://ideiam.com/ I've had the opportunity to met this guys and was really impressed with the prototypes!

Bruno Gouveia

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Re: membrane bass traps thickness
« Reply #20 on: February 03, 2009, 03:51:42 am »

Thomas Jouanjean wrote on Tue, 03 February 2009 07:59




Moreover, they allow to keep the light in - which will make the client happy. If you want, I'll share the results of our first shot at them?


Yes please, don't forget to share with us the results!!

I also love big windows. Natural light is something that I always want to preserve!

Thomas Jouanjean

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Re: membrane bass traps thickness
« Reply #21 on: February 03, 2009, 06:03:28 am »

This a great info exchange Bruno, we keep in touch!
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Thomas Jouanjean
Northward Acoustics - Engineering and Designs
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andrebrito

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Re: membrane bass traps thickness
« Reply #22 on: February 05, 2009, 06:10:18 am »

Bruno,

One thing is to predict the behavior of a box, another to predict the behavior of a box within a room and a sound field all together.

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andrebrito

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Re: membrane bass traps thickness
« Reply #23 on: February 05, 2009, 06:12:49 am »

Meaning by that... lots of packages there for FEM but what really matters is BEM and there are no commercial packages for this yet
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andrebrito

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Re: membrane bass traps thickness
« Reply #24 on: February 05, 2009, 06:15:15 am »

RPG has some micro-absorbing system as well. I have seen them (since I sell their products) but actually never used it in a project
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Bruno Gouveia

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Re: membrane bass traps thickness
« Reply #25 on: February 05, 2009, 06:26:10 am »

andrebrito wrote on Thu, 05 February 2009 11:10

Bruno,

One thing is to predict the behavior of a box, another to predict the behavior of a box within a room and a sound field all together.



To have a tool that to great extent can calculate the vibration a complex structure can be a great help. Like it was said, how it couples with airborne vibration is another variable that we must have in account and likewise difficult to predict without practical experience.

For instance, in many rooms I still can't tell for sure what's causing the reverberation, is it just reflections or is it reactive energy?


andrebrito

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Re: membrane bass traps thickness
« Reply #26 on: February 05, 2009, 07:18:23 am »

Yes , I have used such tools a few times and you can even considered the entire room to be such a structure. The impact it is on the listener is a different stuff.

Anyway I find it too much work to do for a studio recording project and like Thomas I might use computacional acoustics if the client can afford it (usually they cannot lol).

For large room acoustics in sames cases using computacional acoustics is almost mandatory
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Thomas Jouanjean

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Re: membrane bass traps thickness
« Reply #27 on: February 05, 2009, 03:15:41 pm »

Bruno Gouveia wrote on Thu, 05 February 2009 05:26


For instance, in many rooms I still can't tell for sure what's causing the reverberation, is it just reflections or is it reactive energy?


Ah, the joys of re-emission...

Both Smile

The hardest part is when materials store energy and then re-emit periodically at their resonance frequency.

Thomas <- gets a couple aspirins.
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Thomas Jouanjean
Northward Acoustics - Engineering and Designs
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Thomas Jouanjean

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Re: membrane bass traps thickness
« Reply #28 on: February 05, 2009, 03:17:48 pm »

andrebrito wrote on Thu, 05 February 2009 06:18

Anyway I find it too much work to do for a studio recording project and like Thomas I might use computacional acoustics if the client can afford it (usually they cannot lol).


Hell, even the designers have a hard time affording the softwares to start with Rolling Eyes


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Thomas Jouanjean
Northward Acoustics - Engineering and Designs
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Bruno Gouveia

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Re: membrane bass traps thickness
« Reply #29 on: February 05, 2009, 03:31:06 pm »

Thomas Jouanjean wrote on Thu, 05 February 2009 20:15



Ah, the joys of re-emission...

Both Smile

The hardest part is when materials store energy and then re-emit periodically at their resonance frequency.



Ehehehh! One of the most acoustical clear experiences I had was when a room that was being built, the walls were just cement blocks and the room was sounding good. When the blocks were covered with MDF, reverberation time at bass frequencies tilted up. The MDF was really loose so the it was clear where the undesired effect came.

There's another story though, that still makes me think a lot. Casa da M
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